Normal consciousness relies, at least in part, on the brain’s Default Mode Network (DMN), according to neuroscientist Robin Carhart-Harris, head of psychedelic research in the brain sciences division of the Imperial College of London medical school. The DMN is a network of interacting brain regions that acts as a cognitive transit hub, integrating and assimilating information. As the name implies, it’s the usual system of organization for your mind. Carhart-Harris says the DMN “gives coherence to cognition” by connecting different regions of the brain, and is considered the “orchestrator of the self.”

Carhart-Harris and his colleagues found what seems to be an important function of the DMN inadvertently. While studying brain networks, they got curious about what changes might occur when people are under the effects of hallucinogens. In studies analyzing the effects of psilocybin on brain wave oscillation and blood flow, they found that when the DMN was inactive, an alternate network of consciousness seemed to arise.

When some study subjects tested psilocybin, they reported a strong sense of interconnectedness, as well as spiritual, magical, and supernatural feelings.

In the alternate mode, brains produced a different world that offered other sensations and realizations than in everyday life. In this mode, the self wasn’t the protagonist of the narrative. Meanwhile, scans of blood flow and brain wave oscillations showed new, unusual—but orderly and synchronous—connections forming between cortical regions, as if the brain was reorganizing its network. This led Carhart-Harris to posit that the DMN generates the feeling we each have that we’re individuals, a feeling that manifests very strongly as reality. And that means we can temporarily switch off, or mute, this part of the brain.

According to the famous work of Roger Sperry and Michael Gazzaniga, “split brain” patients seem to experience a split in consciousness: the left and the right side of their brain can independently become aware of, and respond, to stimuli. Split brain patients are those who underwent surgery to sever the corpus callosum, the nerve tract connecting the two hemispheres of the brain.